Adds likes in vis items
adds hearts to the sprites css
reorganices code
adds placeholder method
animation
makes animation faster
improves name of classes
makes the animation more interesting
Merge branch 'master' into 1038-likes

Conflicts:
	lib/assets/javascripts/cartodb/dashboard/views/table_list_item.jst.ejs
#1335 Created DB table
#1335 ongoing basic ops for liking/disliking
#1335 Basic features & specs done, going for API endpoints
#1335
Add resque-metrics gem
Adds specs
add likes variables
allows to like visualizations
changes class name
test vis like
Add resque fork metrics too